Tube forming apparatus

ABSTRACT

A TUBE FORMING APPARATUS IS DISCLOSED WHICH INCLUDES A ROTATABLE MOLDING CHAMBER AND MEANS FOR FEEDING A CONTINUOUS FIBER FILAMENT INTO THE MOLDING CHAMBER AT A PREDETERMINED FEED RATE WHICH IS LESS THAN THE SURFACE SPEED OF THE MOLDING CHAMBER TO DEPOSIT THE FIBER FILAMENT ONTO THE INNER SURFACE OF THE MOLDING CHAMBER IN A PREDETERMINED PATTERN. A CONVEYOR MEANS DISTRIBUTES CHOPPED FIBERS OVER THE COILED CONTINUOUS FILAMENT, AND A THERMOSETTING RESIN IS SUPPLIED TO THE MOLDING CHAMBER TO IMPREGNATE THE CONTINUOUS FIBER FILAMENT AND THE CHOPPED FIBERS.

,1971 A.J.WILTSHIRE 3,555,614

TUBE FORMING APPARATUS Original Filed June 22. 1964 9 Sheets-Sheet 1 I sA g A R 2 8 0 m 53 Q E S i .b A 8 E E g i 3 l J INVENTOR.

a ARTHUR J. WILTSHIRE 3 Q BY W m W ATTORNEYS Jan- 1971 A. J. WILTSHIRE55,614

TUBE FORMING APPARATUS I Original Filed June 22 1964 9 Sheets-Sheet :5

INVENTOR.

ARTHUR J. WILTSHIRE Jan. 19-, 1971 A. J. WILTSHIRE 3,555,614

TUBE FORMING APPARATUS I Original File d June 22, 1.964 9 Sheets-Sheet 4ig. 2b

INVENTOR.

ARTHUR J. WILTSJIIRE BYWWIJWQ v L W ATTORNEYS Jan. 19, 1971 A. J.WILTSHIRE 3,555,614

TUBE FORMING APPARATUS Original Filed June 22 1964 9 Sheets-Sheet 5 \QINVENTOR. ARTHUR J. WILTSHIRE w ATTORNEYS A. J. WILTSHIRE 3,555,614

TUBE FORMING APPARATUS 9 Sheets-Sheet 6 I l I INVENTOR. ARTHUR JWILTSHIRE Y )I-Cm A 3%;

7 1 {.aml/ V d is -J d ATTORNEYS HHHIIIII I nD P Jan. 19, 1971 OriginalFiled June 22, 1964 1971 A. J. WILTSHIRE 3,555,614

TUBE FORMING APPARATUS Original Filed June 22 1964 9 Sheets-Sheet '7Jan. 19; 1971 4 A. J. w lRE 3,555,514

TUBE FORMING APPARATUS Original Filed June 22v L964 9 Sheets-Sheet 8III/II I/ I 64 i 111/] FL Fig. 7

INVENTOR.

ARTHUR J. WILTSHIRE ATTORNEYS Original Filed June 22 1964 Jan. 19, 1971A. J. WILTSHIRE r 3,555,614

TUBE FORMING APPARATUS 9 Sheets-Sheet 9 Fig- 9 INVENTOR.

ARTHUR J. WILTSHIRE United States Patent 3,555,614 TUBE FORMINGAPPARATUS Arthur J. Wiltshire, Cleveland, Ohio, assignor to StructuralFibers, Inc., Chardon, Ohio, a corporation of Ohio Original applicationJune 22, 1964, Ser. No. 376,918.

Divided and this application Nov. 18, 1968, Ser.

Int. Cl. B28]: 21/32 US. Cl. 18-26 8 Claims ABSTRACT OF THE DISCLOSUREThis application is a divisional application of US. patent applicationSer. No. 376,918, filed June 22, 1964, and now abandoned.

This invention relates generally to the manufacture of fiber-reinforced,seamless articles and, more particularly, pertains to the manufacture offiber-reinforced plastic tubes which are fabricated by laying up acontinuous fiber filament and randomly oriented chopped fibers within ahollow, cylindrical mold, impregnating the chopped fibers and continuousfilament with a thermosetting resin, and heating the resin-impregnated,laid-up fibers and filament to set the resin.

The invention constitutes an improvement in the methods and articlesproduced in accordance with the teachings set forth in my copendingapplication Ser. No. 278,382.

One of the commercial applications of the invention described andclaimed in the aforementioned application is in the manufacture ofdomestic water softener tanks and similar large, Watertight andchemically resistant, hollow objects. In general, the preferred tankstructures are elongated cylinders having outwardly convex end walls, atleast one of the end walls having a central opening therein forcommunication with the interior of the tank.

According to the methods described in the above-mentioned application,the hollow tanks are successfully and economically produced by providinga fiber-reinforced, molded plastic shell and by winding a continuousfiber filament on the cylindrical sidewall of the shell at approximately90 to the axis of the shell.

The molded shell is produced by laying up fiber matting in theapproximate form of the desired object and encasing this form within arigid, open-end, cylindrical mold casing. An expandable bag or envelope,or other fluidexpandable membrane, which defines the shape of thefinished article, is positioned within the laid-up form in the mold, andpreformed fiber end Wall caps are telescoped into each end of thelaid-up form. The external cylindrical mold casing is closed by clampingto the ends thereof rigid casing caps which shape the end walls of thetank formed therein. With the mold and fiber preforms thus assembled,the matting is placed under a suitable moderate pressure by expandingthe bag to hold the fiber matting in place against the mold, and thenthe fiber matting is partially permeated with a thermosetting resin orthe like. The bag is subsequently expanded by further inflation toprogressively compress the fiber matting in such a manner as todistribute the resin throughout the matting and achieve the desiredresults of pressure-molding, while, at the same time, avoiding migrationof the fibers and destruction of the laid-up fiber mats. After the fiberbody of the article has been thus impregnated and shaped within themold, and while the shape is maintained by pressure from the bag, thecasing of the mold is usually subjected to heat in order to acceleratesetting of the resin. When the resin has set, the bag is opened to theatmosphere and is thereby collapsed. The upper and lower casing caps arethen removed from the mold casing, the bag is removed through a hole inthe upper end of the formed structure, and the finished molded articleis then slid longitudinally from the mold casing.

As distinguished from prior art tanks generally produced in accordancewith this pressure-molding technique, the molded shell, according to mycopending application, is designed to withstand only the longitudinalstresses that result from a predetermined internal pressure. The shellthat is initially provided in accordance with the teachings of myabove-mentioned application, therefore, has a wall thickened that isapproximately one-half the thickness of the prior art tanks. Theresin-impregnated filaments that are wound about this shell are intendedto support substantially all of the hoop stresses that the cylindricalwall is to support. This procedure produces a finished seamless tankhaving a cylindrical wall in which all of the longitudinal stresses arecarried by the shell and substantially all of the circumferentialstresses are carried by the circumferential winding. The resulting tankwall is approxi mately fifty percent lighter than a tank wall of equalhoop strength (the critical consideration) formed by impreg nated glassfiber matting alone.

The production of tanks in accordance with my abovementionedapplication, however, involves two separate manufacturing steps, i.e.,molding the shell and winding continuous filaments on the molded shell.The formation of the shelf itself, furthermore, involves the laboriousand time-consuming steps of laying up a fibrous preform within a moldcasing, positioning an expandable bag in the preform, and injecting thelaid-up fiber form with a thermosetting resin, as is set forth above.This plastic impregnated fiber form, furthermore, must be hardened priorto the filament winding operation so that the shell acts as a rigidmandrel during the winding step.

The present invention has for its main objective the provision ofimprovements in the methods disclosed in the above application toproduce seamless tanks having improved strength and Weightcharacteristics and to produce the cylindrical sidewall of the tanks bya centrifugal molding technique.

A more specific object of the present invention is to provide animproved method of fabricating a tank and improved apparatus forcarrying out the method that eliminate circumferential windingtechniques and the use of fiber preforms.

In general, these objectives are attained by laying down a continuousfiber filament within a rotating, cylindrical mold and, simultaneously,impregnating the filament with a suitable thermosetting resin. After thefilament is laid on the cylindrical sidewall of the mold in any desiredpattern, randomly oriented, chopped fibers and a suitable thermosettingresin are introduced into the mold and onto the laid-up,resin-impregnated continuous filament. The rotating mold is then heatedto fully cure the resin and produce a resin-impregnated tank sidewallhaving a continuous filament outer layer and a randomly oriented fiberinner layer. Alternatively, the continuous filament and chopped fibersmay be laid up in the mold prior to the introduction of resin.

Other objects and advantages of the invention will become apparent fromthe following detailed description and the accompanying drawings.

In the drawings:

FIG. 1a is a side elevation of a portion of the machine in accordancewith the present invention;

FIG. 1b is a side elevation of another portion of the machine accordingto this invention;

FIG. 2a is a top plan view of the portion of the machine shown in FIG.1a;

FIG. 2b is a top plan view of the portion of the machine shown in FIG.lb;

FIG. 3 is a sectional view, the plane of the section being indicated bythe line 33 in FIG. 1a;

FIG. 4 is a sectional view, the plane of the section being indicated bythe line 44 in FIG. 2a but showing the filament feeding device in anoperating position within the mold;

FIG. 5 is a sectional view of the machine, the plane of the sectionbeing indicated by the line 5-5 in FIG. 4;

FIG. 9 is a sectional view of a finished pressure vessel producedaccording to the present invention.

Referring now to the drawings, and particularly to FIGS. 1a and 1b, atube molding machine is illustrated. The machine 20 includes a filamentand resin-feeding portion 21, a mold portion 22, and a chopped fiber andresin-feeding portion 23. The portions 21, 22, and 23 are mounted on abase frame 24.

The filament and resin-feeding portion 21 includes a tube 25 which isslidably mounted in a hollow guide block 26. The guide block 26 is fixedto a vertically mounted plate 27, which plate is in turn fixed to thebase frame 24. A variable speed, D.C. reversing motor 28 is mounted onthe guide block 26. The motor 28 is provided with a built-in speedreducing mechanism and has a pinion gear 29 provided on the end of itsoutput shaft. The pinion gear 29 engages a gear rack 30, which ismounted on one side of the tube 25. The hollow guide block 26 has aninternal channel (not shown) which slidably receives the gear rack 30and has an opening 31 in its side to permit the pinion gear 29 to engagethe rack 30.

A shelf 32 is fixed to one end of the tube 25 and the shelf 32 supportsroving cakes 33. A continuous filament 34 is trained from one of theroving cakes 33 through a guide eye 35, and into a hollow tube 36. Asolenoidoperated cutter 37 is mounted on the shelf 32 between the guideeye 35 and the open mouth of the hollow tube 36. The tube 36 is fixed tothe tube 25 and extends through the plate 27 and the hollow guide block26. An air line 38 leads into the tube 36 to train the filament 34through the tube 36 by air pressure.

The splined shaft 43 (FIG. 4) has an end portion which projectsoutwardly from the bearing 46 and this projecting end portion isprovided with a bevel gear 100 which meshes with another bevel gear 101.The bevel gear 101 is mounted for rotation on a plate 102, which isfixed to and projects outwardly from the end of the tube 25. The bevelgear 101 meshes with a bevel gear (not shown) which is associated with adrive roll 103 to rotate the roll 103 in a clockwise direction as viewedin FIG. 4. The filament 34 is fed from the end of the tube 36 andbetween the drive roll 103 and an idler roll 104 and into a narrow mouthportion 105 of a guide bell 106 which is fixed to the end of the plate102.

A resin feed tube 39 is fixed to the bottom of the tube 25 and extendsthrough the plate 27 and the hollow guide 4 block 26. A resin tank 40 isconnected to the feed tube 39 by a flexible hose 41. An air pressureline 42 is connected to the top of the resin tank 40 so that the resincontained therein is fed to the resin feed tube 39 at a constantpressure.

The splined shaft 43 is axially mounted for rotation within the tube 25by bearings 44, 45, and '46, which are respectively provided at one endof the tube 25, at an intermediate portion of the tube 25, and at theother end of the tube 25. A length of the shaft 43 between the bearings44 and 45 is provided with splines 47. The gear 48 is slidably mountedon the spline 47 and is in driving relationship with the shaft 43. Alongitudinal opening 49 is provided in one side of the tube 25 and thegear 48 engages a gear 50 through this opening. The gear 50 isjournalled for rotation on the plate 27 and has a pair of side plates 51which retain the gear 48 in a longitudinally fixed position relative tothe gear 50 and, therefore, the plate 27. The gear 50 is driven by aring gear 52 through an idler gear 53. The ring gear 52 is provided witha mechanical clutch 4 which alternately connects and disconnects thering gear 52 from a main drive shaft 55 in a manner which willhereinafter become apparent.

The drive shaft 5 is journalled to the frame 24 by.

bearings 56 and is driven by a variable speed D.C. motor 57. A phenolicdrive gear 5 8 is fixed to one end of the drive shaft 55 and engages aring gear 59. The ring gear 59 is mounted at one end of a hollowcentrifugal mold 60. The centrifugal mold 60 is provided with endinserts 61 and 62, which have a frustum-shaped inside surface.

The centrifugal mold 60 has annular bearing flanges 63 adjacent each endof the mold. Each bearing flange rests on a pair of phenolic bearingWheels '64, which are mounted for rotation on the base frame 24. The topof each flange is supported by a phenolic bearing wheel 65, which ismounted in line with the vertical axis of the mold 60.

The outer surface of the mold 60 is enclosed by a hood 66. Circulatinghot air is forced into the hood 66 (FIGS. 2a and 5) through an inletopening -67 and is exhausted through an opening 68.

The chopped fiber and resin-feeding portion 23 of the machine 20 is seenmost clearly in FIGS. 1b, 2b, 6 and 8. The portion 23 includes aconveyor frame '69 which is slidably mounted in a hollow guide block 70.The guide block 70 is fixed to a vertically mounted plate 71 which, inturn, is fixed to the base frame 24. A varible speed D.C. reversingmotor 72 is mounted on the hollow guide block 70. The motor 72 has abuilt-in speed reducing mechanism and has a pinion gear 73 mounted onits output shaft. The pinion gear 73 engages a gear rack 74 which isfixed to and extends longitudinally along one side of the conveyor frame69. The pinion gear 73 engages the gear rack 74 through an opening 75which is provided in one side of the guide block 70.

The conveyor frame 69 comprises a pair of spaced vertical plates 76 and77 which are tied together by cross bars 78. A drive roll 79 is mountedfor rotation at one end of the conveyor frame 69 between the plates 76and 77 and is driven by a motor 80. A conveyor belt 81 is wrapped aroundthe drive roll 79 and an idler roll which is mounted for rotation at theother end of the conveyor frame 69.

The edges of the conveyor belt 81 are guided by longitudinal tracks 82which are cut into the spaced vertical plates 76 and 77.

A cutter 83 is mounted on the hollow guide block 70 directly over theconveyor belt 81. The cutter 83 includes a feed roll 84, an anvil roll85, and a cutter roll 86. The feed roll 84 is driven in acounterclockwise direction, as viewed in FIG. 6, by a motor 87. Acontinuous fiber filament 88 is trained from roving cakes '89, through aguide eye 90, and into the bight of the feed roll 84 and the anvil roll85. The filament 88 then passes between the anvil roll 85 and the cutterroll 86 to be chopped into relatively short fibers and dropped on theconveyor belt 81.

A resin feed tube 91 is fixed to the bottom of the plate 76 and extendslongitudinally along the conveyor frame 69. A resin tank 92 is connectedto the feed tube 91 by a flexible hose 93. The space in the tank abovethe level of the resin is maintained under pressure by an air pressureline 94 which is connected to the top of the tank 92. This insures thatthe resin will be fed through the tube 91 at a substantially constantpressure.

OPERATION To form a cylindrical tank sidewall having a circumferentiallywound outer surface and a resin-impregnated, chopped fiber innersurface, the motor 28 is energized to drive the tube 25 into thecentrifugal mold '60. The continuous filament 34 is introduced into themouth of the tube 36 and is forced through that tube by a blast ofpressurized air from the air line 38. The filament 34 is then trainedbetween the drive roll 103 and the idler roll 1 04 and the end of thefilament is fixed to one end of the mold by pressure-sensitive tape.

When the tube 25 is driven to the right hand side of the mold, as viewedin FIG. 4, a limit switch 95, which is mounted on the plate 27, isactuated by a plate 96 which is fixed to the tube 25. When the limitswitch 95 is struck by the plate 96, the polarity of the motor 28 isreversed to drive the tube 25 to the left, as viewed in FIG. 4. Theactuation of the switch 95 also starts the motor 57 to rotate thecentrifugal mold in a counterclockwise direction (FIG. 5) and to causethe drive roll 103 and the idler roll 104 to feed the filament 34 to theinside mold surface. Actuation of the switch 95 also opens a valve (notshown) in the air pressure line 42 to force resin out of the tank 40 andthrough the resin feed tube 39.

The filament that is fed from the end of the tube 25 clings to the innersurface of the mold 60 by proper selection of the surface speeds of themold 60 and the rolls 103 and 104, and forms a predetermined patterndepending upon the operation of the reversing motor 28. For example, ifa tank, having an outside diameter of inches and a circumferentiallywound outer wall, is to be formed the inside diameter of the mold 60would be 10 inches and the mold would be rotated at at least 85 rpm. toovercome the force of gravity on the filament, For a typicalapplication, a 10-inch tank mold would be rotated at 300 rpm. and, witha 1:1 ratio between the gears 58 and 59, the drive shaft 55 would berotated at 300 rpm. The gears 50, 52, 53, 48, 100, 101, and the gear(not shown) associated with the drive roll 103 would all be selected toestablish a 4:1 gear ratio between the drive roll 103 and the driveshaft 55'. This 4:1 ratio permits the use of a 2 /2 inch drive roll andthe insertion of the filament feeding end portion of the tube 25 intothe mold 60. Although the roll 103 is driven at 1200 r.p.m., its surfacespeed corresponds to that of the inside surface of the centrifugal mold60. The roll 103, however, is designed so that its diameter is slightlyless than 2 /2 inches so that the surface speed of the mandrel isslightly greater than that of the roll 103. This relationship insuresthat a controlled loop will be formed on the inner surface of the mold60 since, as may be seen in FIG. 5, the filament 34 will be dragged at avery slow rate in a counterclockwise direction around the inside surfaceof the mold.

If the pattern formed by the filament 34 on the inner surface of themold 60 is to be a hoop or level wound pattern, i.e., a winding in whicheach loop is substantially contiguous to the preceding loop and isoriented at an angle of substantially ninety degrees to the longitudinalaxis of the centrifugal mold 60, the speed of the motor 28 would beadjusted relative to the surface speed of the mold 60 so that the loopsare substantially contiguous. The loops that are laid down on the insidesurface of the mold 60 are impregnated with resin from the resin feedtube 39.

It should be appreciated that, although the gear 48 drives the splineshaft 43 while the tube 25 is being driven to the left by the gear 29,the gear 48 is held in its illustrated position by the side plates 51 onthe gear 50. The operation of the gear 48-, therefore, is not dependentupon or influenced by the motion imparted to the tubes 25 by the motor28.

The filament 34, therefore, may be laid down on the inside surface ofthe mold 60 in any desired pattern by changing the speed and/or thedirection of operation of the motor 28.

When the filament 34 has been laid up on the inside surface of the mold60 in the indicated manner and the tube 25 has been driven to the left,as viewed in FIG. 4, a limit switch 97, which is mounted on the hollowguide block 26, is struck by a plate 97a which is mounted near one endof the tube '25. The operation of the limit switch 97 energizes thesolenoid-operated cutter 37 to sever the filament 34, stops the motor28, and operates the mechanical clutch 54 to disengage the ring gear 52from the drive shaft 55.

With the tube 25 in a retracted and inoperative condition, the motor 72is energized to drive the conveyor frame 69 to the left as viewed inFIG, 6. When a limit switch 98, which is mounted on the support plate71, is struck by a plate 99, which is mounted on the conveyor frame 69,the polarity of the motor 72 is reversed to drive the conveyor frame tothe right as viewed in FIG. 6. Operation of the limit switch 98 alsoenergizes the motor to drive the conveyor belt 81 in the directionindicated by the arrows in FIG. 6, energizes the motor 87 to operate thecutter 83, and opens a valve (not shown) in the air line 94 to forceresin through the feed tube 91.

As the conveyor frame 69 traverses from left to right, as viewed in FIG.6, the inside surface of the resin-impregnated filament 34 is coatedwith randomly oriented, resinimpregnated, chopped fibers. As the choppedfibers are fed from the conveyor belt 81, they are deflected downwardlyby a shield which is provided at the end of the frame 69. A pressurizedair line 111 is connected to the frame 69 to maintain a slight positivepressure within the belt 81 so that the chopped fibers will not foul theconveyor belt or its drive and idler rolls.

The chopped fibers and resin that are distributed on the rotating innersurface of the mold form a cylindrical and relatively thick medialportion between the end inserts 61 and 62. The centrifugal force whichis imparted to the chopped fibers and resin levels the inner surface ofthe resin so that this surface is smooth and cylindrical and so that theends of the relatively thick medial portion are tapered.

When the conveyor frame 69 has been retracted to one end of the mold 60,a limit switch 112, which is mounted on the hollow guide block 70, isstruck by a plate 113 which is mounted on the conveyor frame 69. Theactuation of the limit switch 112 deenergizes the motor 80, the motor87, and the motor 72.

While the mold is still rotating, the temperature of the heated airwithin the hood 66 is raised to increase the temperature of the laid-upfiber-resin form to the setting temperature of the resin, The heated airis circulated through the hood 66 until the resin has fully set.

When the resin has fully set, the motor 57 is turned off to stop therotation of the mold 60. The chopped fiber and resin feeding portion 23of the machine 20 is then further retracted to permit removal of thefinished molded article. To this end, longitudinal slots 114 areprovided in the base frame 24 so that the vertically mounted plate 71may be pulled away from the mold 60 when bolts 115 are loosened.

As may be seen in FIG. 9', a molded, fiber-reinforced, plastic sidewall116 is provided with top and bottom premolded end caps 117 and 118,respectively, to form a finished tank. The top end cap 117 may beprovided with a threaded access opening 119 if the finished tank is tobe employed as a water softener. Each end cap is cup-shaped and includesa cylindrical wall 120 which tapers in cross section from a relativelythick bottom 121 to a relatively thin rim 122. The tapered cylindricalwall 120 of each end cap is cemented to the tapered end portions of thecentrifugally molded article.

Instead of thoroughly impregnating the fibers and filaments with resin,it should be appreciated that the laid-up fibers and filaments may bepartially impregnated with a thermosetting resin. In this instance, theresin acts as a binder to maintain the shape of the fiber form when theresin is cured. The binder-impregnated fiber form may be laid up in acylindrical mold, provided with fiber end caps (or premolded end caps),and then may be thoroughly impregnated with additional resin to form afinished tank.

It is to be understood therefore that the resin impregnation stepreferred to in the following claims is intended to embrace both thoroughand partial resin impregnation.

Many modifications and variations of the illustrated, preferredembodiment of the invention will be apparent to those skilled in the artin light of the above disclosure. Therefore, it is to be understoodthat, within the scope of the appended claims, the invention may bepracticed otherwise than as specifically shown and described herein.

What is claimed is:

1. A molding machine for making a fiber-reinforced molded plasticarticle comprising a molding chamber having a cylindrical inner surfacecomforming to the shape of the sidewall of the finished article, meansfor rotating said molding chamber about its longitudinal axis toestablish a predetermined surface speed for the cylindrical innersurface of said molding chamber, means for feeding a continuous fiberfilament into said molding chamber at a predetermined feed rate ofslightly less than said surface speed of said inner surface of saidmolding chamber to deposit said fiber filament in a continuous strandonto said cylindrical inner surface from a point within said chamber atsaid filament feed rate, and means for moving said point within saidmolding chamber to deposit said fiber filament in a predeterminedpattern on said inner surface of said molding chamber.

2. A molding machine as set forth in claim 1, including means forsupplying a thermosetting resin to said molding chamber to impregnatesaid continuous fiber filament therewith, and means for heating saidmolding chamber to set said resin.

3. A molding machine as set forth in claim 1, wherein said means forfeeding said continuous filament includes a feed roll having a generallycylindrical outer surface disposed within said molding chamber, and ameans for rotating said feed roll at a predetermined rate so that thesurface speed of said feed roll outer surface is less than the surfacespeed of said molding chamber inner surface.

4. A molding machine for making a fiber-reinforced molded plasticarticle comprising a molding chamber having a cylindrical inner surfaceconforming to the shape of the sidewall of the finished article, meansfor rotating said molding chamber about its longitudinal axis toestablish a predetermined surface speed of the cylindrical inner surfaceof said molding chamber, means for feeding a continuous fiber filamentinto said molding chamber at a predetermined feed rate of slightly lessthan said surface speed of said inner surface of said molding chamber todeposit said fiber filament onto said cylindrical inner surface from apoint within said molding chamber at said filament feed rate, means formoving said point within said molding chamber to deposit said filamentin a predetermined pattern on the inner surface of said molding chamber,means for randomly distributing chopped fibers over the coiledcontinuous filament and the inner mold surface, means for supplying athermosetting resin to said molding chamber to impregnate saidcontinuous fiber filament and said chopped fibers therewith, and meansfor heating said molding chamber to set said resin.

5. A molding machine as set forth in claim 4 wherein said means forfeeding said continuous filament includes a feed roll having a generallycylindrical outer surface disposed within said molding chamber, and ameans for rotating said feed roll at a predetermined rate so that thesurface speed of said feed roll outer surface is less than the surfacespeed of said molding chamber inner surface.

6. A molding machine as set forth in claim 4 wherein said means formoving said point orients each revolution of said continuous fiberfilament at an angle of substantially degrees to said longitudinal axisof said molding chamber.

7. A molding machine as set forth in claim 4 wherein said means fordistributing distributes said chopped fibers evenly over a major medialportion of said coiled continuous filament so that they have a uniformlydecreasing bulk from said major medial portion to both ends of saidcylindrical molding chamber to thereby taper the end portion of saidcylindrical sidewall.

8. A molding machine as set forth in claim 4 wherein said means fordistributing chopped fibers includes means for chopping fibers at alocation outside of saidmolding chamber and means for conveying saidchopped fibers from said location into said molding chamber.

References Cited UNITED STATES PATENTS 2,870,054- 1/1959 Amos et al.18-26X 2,994,919 8/1961 Schafer et al l826 3,012,922 12/1961 Wiltshirel826X 3,052,927 9/1962 Hoppe et al. l826 3,112,530 12/1963 Boggs et al.l826 3,206,821 9/1965 Keyser et a1 2530CX 3,133,563 5/1964 Smith 141-123,150,219 9/1964 Schmidt 264258 FOREIGN PATENTS 1,329,371 4/1963 France.

I. SPENCER OVERHOLSER, Primary Examiner US. Cl. X.R.

UNITED STATES PATENT OFFIICE CERTIFICATE OF CORRECTION Dat Januarv 191921 Patent No. 3,555,614

InventorCs) ARTHUR J. WILTSHIRE It is certified that error appears inthe above-identified patent and that said Letters Patent are herebycorrected as shown below:

change change change change change change change "suit able" tosuitably--.

Signed and sealed this 7th day of September 1971.

Column 1, line Column 2, line and line

Column 3, line Column 4, line line line

(SEAL) Attest:

EDWARD M.F'LETCHER, JR.

Attesting Officer ROBERT GOTTSCHALK Acting Commissioner of Paten

